Method and apparatus for determining optimal pacing therapy timing intervals

• US 20070179542A1
• Filed: 01/31/2006
• Published: 08/02/2007
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Prakash, Rajan, Chinchoy, Edward, Mullen, Thomas
• Granted Patent: US 7,653,437 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay

Abstract

A method for determining an optimal pacing timing control parameter setting is provided for use in an implantable medical device programmed to deliver a pacing pulse in response to the timing control parameter. The method includes storing a user-selected optimization metric, iteratively adjusting the timing control parameter setting, sensing a first signal that varies in response to left ventricular wall acceleration, measuring the user-selected optimization metric in response to the sensed first signal, and determining an optimal timing control parameter value in response to the measured user-selected optimization metric.

Claims

1. A method for use in an implantable medical device programmed to deliver a pacing pulse in response to a timing control parameter, comprising:

storing a user-selected optimization metric;

iteratively adjusting the timing control parameter;

sensing a first signal that varies in response to left ventricular wall acceleration;

measuring the user-selected optimization metric in response to the sensed first signal; and

determining an optimal timing control parameter value in response to the measured user-selected optimization metric.

2. A method according to claim 1 wherein measuring the user-selected optimization metric includes setting a first signal sensing window in response to the user-selected optimization metric.

3. A method according to claim 1 wherein measuring the optimization metric includes measuring one of:

a first maximum peak, a second maximum peak, a first minimum peak, a second minimum peak, a slope, a morphological signature, a threshold crossing, an inflection point, and a temporal separation of the first maximum peak and the second maximum peak.

4. A method according to claim 1 wherein storing the user-selected optimization metric includes storing a user-selected cardiac cycle phase to be optimized.

5. A method according to claim 1 wherein measuring the user-selected optimization metric includes verifying a predetermined stability requirement.

6. A method according to claim 5 wherein the predetermined stability requirement includes at least one of:

a heart rate, a pacing mode, a respiration rate, an activity level, a time of day, a posture.

7. A method according to claim 1 wherein measuring the user-selected optimization metric includes minimizing the effect of non-cardiac signal contributions to the first sensed signal.

8. A method according to claim 7 wherein minimizing the effect of non-cardiac signal contributions includes sensing a second signal that varies in response to non-cardiac motion.

9. A method according to claim 1 further including determining a heart rate and wherein measuring the user-selected optimization metric in response to the sensed first signal includes measuring the user-selected optimization metric at a plurality of heart rates and wherein determining the optimal timing control parameter value in response to the measured user-selected optimization metric includes determining the AV delay in response to the heart rate.

10. A method according to claim 1 further comprising:

storing a second optimization metric;

sensing a second signal that varies in response to cardiac function; and

measuring the second optimization metric in response to the second signal, and

wherein determining the optimal timing control parameter value includes determining the optimal timing control parameter value in response to the second optimization metric.

11. A method according to claim 10 wherein the second signal includes any of a left ventricle acceleration signal, a right ventricle acceleration signal, a pressure signal, an impedance signal, a flow signal, and a blood chemistry signal.

12. A method according to claim 1 wherein the timing control parameter includes an AV delay.

13. A method according to claim 1 further including:

determining if the optimal timing control parameter value results in an improvement in the optimization metric, and

responding to determining if the optimal timing control parameter value results in an improvement in the optimization metric wherein the response includes one of programming the timing control parameter to the optimal value in response to determining an improvement in the optimization metric and altering an operating mode of the implantable medical device in response to determining no improvement in the optimization metric.

14. A method according to claim 1 wherein storing the user-selected optimization metric includes storing a pacing mode.

15. A method according to claim 1 wherein storing the user-selected optimization metric includes storing a physiologic condition.

16. A method according to claim 15 wherein the physiologic condition is one of heart rate, metabolic activity, posture, and blood pressure.

17. A method for use in an implantable medical device programmed to deliver a ventricular pacing pulse following an atrial-ventricular (AV) delay, comprising:

iteratively adjusting the AV delay,

sensing a transducer signal that varies in response to left ventricular wall acceleration;

setting a first sensing window corresponding to a first cardiac cycle phase;

determining an optimal AV delay zone in response to the sensed signal occurring during the first sensing window;

setting a second sensing window corresponding to a second cardiac cycle phase; and

determining an optimal AV delay setting within the determined optimal AV delay zone in response to the sensed signal occurring during the second sensing window.

18. A system for providing a cardiac stimulation therapy, comprising:

a programmable memory for storing a user-selected optimization metric;

an output circuit for providing a pacing stimulus to a ventricular heart chamber in response to a timing control parameter;

a first transducer for sensing acceleration of a portion of a left ventricle and providing a first signal related to the acceleration;

an input circuit for receiving the first transducer signal; and

a processor for determining the user-selected optimization metric in response to the first transducer signal received by the input circuit and for determining an optimal timing control parameter value in response to the user-selected optimization metric.

19. A system according to claim 18 wherein the first transducer includes an accelerometer disposed along the left ventricular free wall.

20. A system according to claim 18 further including means for verifying a stability requirement.

21. A system according to claim 20 wherein the means for verifying the stability requirement includes any of an activity sensor, a clock, a posture sensor, a heart rate detector and a respiration rate detector.

22. A system according to claim 18 further including means for minimizing the effect of non-cardiac acceleration signals on the first transducer signal.

23. A system according to claim 22 wherein the means for minimizing the effect of non-cardiac acceleration signals includes a second transducer adapted to be disposed at a non-cardiac location.

24. A system according to claim 18 further including a heart rate detector and wherein the processor determines the optimal timing control parameter value for a plurality of heart rates.

25. A system according to claim 18 further including a second transducer for sensing a second signal related to cardiac function and wherein the processor determines a second optimization metric in response to the second signal and determines the optimal timing control parameter value in response to the second optimization metric.

26. A system according to claim 18 wherein the timing control parameter includes an AV delay.

27. A system according to claim 18 further including:

means for determining if the optimal timing control parameter value results in an improvement in the optimization metric, and

means for responding to determining if the optimal timing control parameter value results in an improvement in the optimization metric wherein the response includes one of programming the timing control parameter to the optimal value in response to determining an improvement in the optimization metric and altering an operating mode of the implantable medical device in response to determining no improvement in the optimization metric.

28. A system according to claim 18 wherein storing the user-selected optimization metric includes storing a pacing mode.

29. A system according to claim 18 wherein storing the user-selected optimization metric includes storing a physiologic condition and further including means for determining the physiologic condition.

30. A system according to claim 29 wherein the physiologic condition is one of heart rate, metabolic activity, posture, and blood pressure.

31. A computer readable medium for storing a set of instructions which when implemented in an implantable medical device system cause the system to:

iteratively adjust a timing control parameter value,

sense a transducer signal that varies in response to left ventricular wall acceleration;

set a first sensing window corresponding to a first cardiac cycle phase;

determine an optimal timing parameter value zone in response to the sensed signal occurring during the first sensing window;

set a second sensing window corresponding to a second cardiac cycle phase; and

determine an optimal timing parameter value within the determined optimal timing parameter value zone in response to the sensed signal occurring during the second sensing window.